1. Field of the Invention
The present invention is directed to a method for manufacturing a porous silicon component which guarantees reliable contacting of the porous silicon.
2. Description of the Prior Art
Silicon is an indirect semiconductor having a band gap of 1.1 eV. The manufacture of semiconductor structures for light emission in the visible spectral range using silicon has heretofore not been thought possible by those knowledgeable in the art.
The production of porous silicon is known in the art from V. Lehman et al. Appl. Phys. Lett. 58, p. 856 (1991). Porous silicon is formed at the surface of a silicon wafer by anodic etching of single-crystal silicon in a fluoride-containing, acidic electrolyte in which the silicon wafer is connected as anode. Porous silicon comprises pores or canals. The diameter of the canals is dependent on the doping of the silicon wafer. Given a doping of the silicon wafer in the range between 10.sup.15 and 10.sup.18 cm.sup.-3 yields canals having diameters from 1-2 nm. Canals having diameters of 10 nm-100 nm arise in silicon with a doping of more than 10.sup.19 cm.sup.-3.
It has been discovered (see v. Lehmann et al., Appl. Phys. Lett. 58, p. 856 (1991)) that porous silicon produced from lightly doped silicon with a dopant concentration between 10.sup.15 and 10.sup.18 cm.sup.-3, and therefore having channels with diameters from 1-2 nm, has a band gap of approximately 1.7 eV and exhibits photoluminescence in the visible spectral range (See L. T. Canham Appl. Phys. Lett. 57, p. 1046 (1990) and N. Koshida et al., Jap. J. Appl. Phys. 30 p. L1221 (1991)).
An optical semiconductor component with porous silicon using a layer of porous silicon with Schottky contacts by vapor-deposition of gold has been proposed (see the press release of the Fraunhofer Inst. IFT. Sueddeutsche Zeitung, No. 199, p. 37, Aug. 29, 1991). The vapor deposition of metal, however, is difficult because of the porosity of the porous silicon.